1. Field of the Invention
Embodiments of the invention relate to gate valves. In particular, embodiments of the invention relate to the retention of a seat member in a gate valve body pocket using a pin or other retaining member that is disposed in a groove in the gate valve body pocket.
2. Description of the Related Art
A gate valve includes a gate that is moved by an operator or actuator in and out of the valve body, often by using a handwheel, to control the flow of fluid or gas through the gate valve. The gate valve also includes an annular or ring-shaped seat member that seals between the gate and a pocket (e.g. a recessed area) within the valve body, referred to as a valve body pocket. One or more seat members are typically housed in the valve body pocket and operate to form a seal with the gate. Seat members for gate valves are typically held in place through use of retainer rings (or plates). Alternatively, the seat members may be free floating within the gate valve and are supported by the gate and the valve body pocket.
Embodiments of the invention disclosed herein relate to replacing the retainer ring type of support. Such retainer rings are slightly larger in circumference than the seat member and are semi-elastic so that the seat member will be held in place within the valve body pocket through an interference fit. The downside of these retainer rings is that the elasticity of the retainer ring can decline over time, or if the retainer rings are used in an environment where significant amounts of lubricants are used, the firmness of the fit may decline over time and the seat members may not stay in place in applications involving high pressure. Therefore, there is a need for new and improved apparatus and methods of retaining seat members within the valve body pockets.